OBJECTIVES: The primary objectives of this project are: to find solutions to basic physics, dosimetry, and clinical problems in the treatment of cancer with charged particle beams (pions, heavy ions, and protons); to design and build a calorimeter for the absolute calibration of charged particle beams; and to compare charged particle beams of various facilities so that a common dose standard can be developed for the treatment of patient dose at all facilities. APPROACH: Physicists throughout the world are engaged in this collaborative research effort. They are either already working actively on projects where patients are already being treated with charged particle beams or they are making serious efforts to develop such projects.